Method for filling a via opening or contact opening in an integrated circuit

Abstract

An integrated circuit includes a substrate ( 12 ) having a conductive region ( 18 ), and includes a dielectric layer ( 19 ) disposed over the substrate. An upwardly tapering frustoconical opening ( 22 ) is created through the dielectric layer to the conductive region. A barrier layer ( 31 ) is then applied, after which a thin metal layer ( 32 ) is applied, the upper end of the opening being pinched off or closed by the metal layer. Heat and pressure are then simultaneously applied, so that the metal layer flows to completely fill the available space within the opening. Selected portions of the metal layer external to the opening are then etched away. A further dielectric layer ( 41 ) is applied over the barrier layer and metal layer, and then planarization is carried out on the further dielectric layer.

What is claimed is:  
     
       1. A method for fabricating an integrated circuit, comprising the steps of: 
       providing a base structure which includes a conductive portion;  
       depositing a first layer of nonconductive material over the conductive portion, the first layer of nonconductive material having a surface on an upper side thereof;  
       creating a cylindrical opening through the first layer of nonconductive material to the conductive portion;  
       depositing a second layer of the nonconductive material over the first layer of the nonconductive material and within the cylindrical opening to create an upwardly converging frustoconical surface within the cylindrical opening;  
       etching the second layer of nonconductive material until a portion thereof on the surface of the conductive portion has been removed to create an upwardly converging frustoconical opening through the nonconductive material from the conductive portion;  
       depositing over the nonconductive material a metal layer which has a portion covering exposed surfaces of the opening; and  
       thereafter simultaneously applying heat and pressure to cause the metal layer to flow to fill available space within the opening.  
     
     
       2. A method according to claim  1 , wherein an open end of the opening is closed off by the metal layer during said depositing a metal layer step. 
     
     
       3. A method according to claim  1 , including after said step of simultaneously applying heat and pressure the additional steps of applying a photoresist to the metal layer, etching the metal layer, removing the photoresist, applying a nonconductive layer, and carrying out a planarizing process on the nonconductive layer. 
     
     
       4. A method according to claim  1 , wherein the nonconductive material is silicon dioxide. 
     
     
       5. A method according to claim  1 , including between said steps of etching and depositing a metal layer, the step of depositing a barrier layer over the nonconductive material, the metal layer being deposited over the barrier layer. 
     
     
       6. A method according to claim  5 , wherein said depositing a metal layer step includes the step of forming the portion of the metal layer on the barrier layer with a thickness which is in the range of 2,000 Å to 12,0000 Å. 
     
     
       7. A method according to claim  5 , wherein said depositing a metal layer step is carried out by using one of aluminum and copper as the metal layer, and includes the step of forming the portion of the metal layer on the barrier layer with a thickness which is in the range of 2,000 Å to 12,000 Å. 
     
     
       8. A method according to claim  5 , wherein the barrier layer is made from one of titanium nitride, tungsten nitride, and tantalum nitride. 
     
     
       9. A method for fabricating an integrated circuit, comprising the steps of: 
       providing a base structure which includes a conductive portion;  
       depositing a first layer of nonconductive material over the conductive portion, the first layer of nonconductive material having a surface on an upper side thereof;  
       creating a cylindrical opening through the first layer of nonconductive material to the conductive portion;  
       depositing a second layer of the nonconductive material over the first layer of the nonconductive material and within the cylindrical opening to create an upwardly converging frustoconical surface within the cylindrical opening;  
       etching the second layer of nonconductive material until a portion thereof on the surface of the conductive portion has been removed to create an upwardly converging frustoconical opening through the nonconductive material from the conductive portion;  
       depositing over the nonconductive material a barrier layer which covers exposed surfaces in the opening;  
       thereafter depositing over the barrier layer a thin layer of aluminum which closes off the opening at an upper end thereof; and  
       thereafter simultaneously applying heat and pressure to cause the aluminum layer to flow to fill available space within the opening.  
     
     
       10. A method according to claim  9 , including after said step of simultaneously applying heat and pressure the additional steps of applying a photoresist to the aluminum layer, etching the aluminum layer, removing the photoresist, applying a nonconductive layer, and carrying out a planarizing process on the nonconductive layer. 
     
     
       11. A method for fabricating an integrated circuit, comprising the steps of: 
       providing a base structure which includes a conductive portion and includes a nonconductive material over the conductive portion, the nonconductive material consisting of silicon dioxide having a surface on an upper side thereof;  
       creating an upwardly converging frustoconical opening through the silicon dioxide from the conductive portion;  
       depositing over the silicon dioxide a metal layer which has a portion covering exposed surfaces of the opening; and  
       thereafter simultaneously applying heat and pressure to cause the metal layer to flow to fill available space within the opening.  
     
     
       12. The method according to claim  11 , including between said steps of creating and depositing, the step of depositing a barrier layer over the nonconductive material, the metal layer being deposited over the barrier layer. 
     
     
       13. The method according to claim  12 , wherein said depositing step includes the step of forming the portion of the metal layer on the barrier layer with a thickness which is in the range of 2,000 Å to 12,000 Å. 
     
     
       14. The method according to claim  12 , wherein said depositing step is carried out by using one of aluminum and copper as the metal layer, and includes the step of forming the portion of the metal layer on the barrier layer with a thickness which is in the range of 2,000 Å to 12,000 Å. 
     
     
       15. The method according to claim  12 , wherein the barrier layer is made from one of titanium nitride, tungsten nitride, and tantalum nitride. 
     
     
       16. The method according to claim  11 , wherein an open end of the opening is closed off by the metal layer during said depositing step. 
     
     
       17. The method according to claim  11 , including after said step of simultaneously applying heat and pressure the additional steps of applying a photoresist to the metal layer, etching the metal layer, removing the photoresist, applying a nonconductive layer, and carrying out a planarizing process on the nonconductive layer. 
     
     
       18. A method for fabricating an integrated circuit, comprising the steps of: 
       providing a base structure which includes a conductive portion and includes a nonconductive material over the conductive portion, the nonconductive material consisting of silicon dioxide having a surface on an upper side thereof;  
       creating an upwardly converging frustoconical opening through the silicon dioxide from the conductive portion;  
       depositing over the silicon dioxide a barrier layer which covers exposed surfaces in the opening;  
       thereafter depositing over the barrier layer a thin layer of aluminum which closes off the opening at an upper end thereof; and  
       thereafter simultaneously applying heat and pressure to cause the aluminum layer to flow to fill available space within the opening.  
     
     
       19. The method according to claim  18 , including after said step of simultaneously applying heat and pressure the additional steps of applying a photoresist to the aluminum layer, etching the aluminum layer, removing the photoresist, applying a nonconductive layer, and carrying out a planarizing process on the nonconductive layer.